The present invention relates to an envelope transport unit in a postage meter.
In a postage meter, a print head is used to produce a postal indicia on an envelope when the envelope is in the print zone. In general, prior to the printing of the indicia, the postage meter must gather postage and other mail related information in order to generate print data necessary to produce the indicia.
A postage meter has to complete a single transaction each time an envelope is processed, and as such it is a real-time system. In general, a transaction includes the following tasks:
1) collection of the parameters of the transactionxe2x80x94Date, postage data, and other pertinent information, such as piece count, postage meter number, originating zip code, etc. must be retrieved from the meter stored memory;
2) generation of tokensxe2x80x94An encryption process is used to generate encrypted numbers, or tokens, that are unique to each single real-time transaction. Two sets of tokens, for example, are generated from the indicia data: one related to a vendor encryption key and one related to a U.S. Post Office encryption key;
3) message preparationxe2x80x94An encrypted signed message is prepared for transmission to the print head that ties together with encryption, all of the information to be contained within the indicia;
4) message transmissionxe2x80x94The encrypted message is sent to the print head for printing after its authenticity has been verified; and
5) data loadingxe2x80x94Once the data has been verified, it must be loaded into the registers of a Draw on the Fly (DOF) ASIC prior to printing. These registers determine the location and content of the printed information within the indicia.
All of the above-mentioned steps, which make up the transaction, take time to complete. Depending on the processing electronics in the postage meter, this transaction time is typically on the order of 200 to 500 msec. But it may be shorter or longer depending upon the particular type of processing electronics being employed and variances any concurrent demands on the processing electronics.
Postage meter customers typically evaluate many factors in making their purchasing decisions. One factor is throughput. It is desirable for the postage meter to be able to process envelopes at a sufficiently high rate to meet the mailing requirements of the customer. Another factor is size. Since desk office space is at a premium, it is desirable for the postage meter to be as small as possible. Yet another factor is cost. To be competitive in the market, the postage meter must be cost effective in view of other payment systems (permit, stamp, private carrier invoicing, etc.). With respect to lower volume mailers, these factors become even more significant.
A significant factor contributing to the size of the postage meter is the length of the envelope transport system. In a lower volume postage meter where the total transport length for the envelope to be transported from the input end of the postage meter to the print zone is reduced, and the envelope speed in the print zone is about 20 in/sec, the transaction time of 200 to 500 msec may cause a problem. If the envelope is transported through the metering system at a speed of 20 in/sec, then it takes only 125 msec for the envelope to travel from the input end to the print zone. This means that there is insufficient time for the processing electronics to complete the transaction before the envelope reaches the print zone.
One solution to this problem is to reduce the speed by approximately one half thereby allowing the processing electronics 250 msec or longer to complete the transaction. However, if the print head requires a certain printing speed such as that required by an inkjet print head to achieve a certain resolution, reducing the envelope speed is not an option. Furthermore, reducing the envelope speed increases the time for the envelope to be ejected after printing, and the transport time in general. That could substantially reduce the efficiency, or the throughput, of the postage meter.
Another solution could be to redesign the processing electronics to accommodate the shorter transport device by completing its operations within the allowed time frame. However, this adds greatly to the overall cost of the postage meter because increased performance typically is achieved by migrating to higher speed microprocessors at increased cost.
It is desirable to have a high efficiency postage metering system in which the envelopes are transported through the print zone at a speed required by the desired throughput characteristics and in which there is sufficient time allowed for the processing means to complete the transaction before the envelope enters the print zone.
The present invention provides a method and a device for improving the efficiency of a postage meter wherein the envelopes are transported in a controlled fashion, so as to allow data processing means to have sufficient time to complete a transaction without reducing the envelope speed in the print zone. The method, according to the present invention, uses a multi-speed profile to match the time requirement of different components of a postage meter. With such a multi-speed profile, the envelope can be transported at a lower speed near the input end to allow the processing electronics to complete the transaction and then the envelope is accelerated to the required printing speed before the envelope is in the print zone. Advantageously, the envelope may be caused to pause at a location between the input end and the print zone to wait for the completion of the transaction.
The improved method as discussed hereinabove is made possible by a transport device, according to the present invention. As a part of the improved postage metering system, the transport device includes means for transporting an envelope from the input end of the postage metering system to the print zone for printing, and transporting the envelope from the print zone to the exit end after printing. The transport device further includes means for controlling the motion of the transporting means in accordance with a multi-speed profile so as to allow sufficient time for the processing electronics to complete the transaction prior to transporting the envelope into the print zone. The multi-speed profile is also designed such that the envelope is transported through the print zone at a speed required by or compatible with the characteristics of the print head. The transport device further includes means for sensing at least one edge of the incoming envelope so as to initiate the multi-speed profile.
With the transport device as discussed above, the method of improving the efficiency of a postage meter can be implemented, which in includes the steps of:
1) sensing at least one edge of the envelope; and
2) controlling the speed of the envelope responsive to said sensing and in accordance with a multi-speed profile so as to allow sufficient time for the data processing means to process mail related data and to provide the mail related data to the print head before or at the time the envelope enters the print zone. Preferably, the multi-speed profile includes a deceleration of the envelope prior to the mail related data being provided to the print head, and an acceleration of the envelope to the required speed prior to the envelope entering the print zone and the printing by the print head. The speed of the envelope prior to the deceleration is, preferably, smaller than or equal to the required speed in the print zone. But it can be greater than the required print zone speed, if so desired. Furthermore, the multi-speed profile may include a pause period after the deceleration.
The method and device for improving the efficiency of a postage meter will become apparent upon reading the drawings and the accompanying description.